NEWARK — Gerardo Gomez made his way to a Newark schoolyard on Aug. 4, 2007, not to rob, brutalize and kill total strangers as he is charged with doing, but to pick up cash from an older cousin to see a movie, his defense attorney insisted today in court.

"It was supposed to be a movie, not a murder. A birthday sleepover with two friends, not this," the attorney, Michael Robbins, told the jury at the start of Gomez’s murder trial in Superior Court in Newark.

"Who could have expected that Gerardo’s 15th birthday would be one that he’d never forget?" Robbins said. "That this happy night would end with such grief and such pain ... Unknown to him, he was walking toward something and into something sudden, shocking and unimaginable. Something he would have no control over, that was conceived of and carried out by others."

But Essex County Assistant Prosecutor Thomas McTigue countered that Gomez was not a mere observer.

"This is a case of children killing other children," McTigue said. "And killing them with shocking violence."

Gomez is the last — and youngest — of six defendants to face justice in the execution-style shooting of four college-aged friends behind the Mount Vernon Elementary School. Only one survived. The other defendants who faced the same murder, attempted murder and robbery counts have either been convicted at separate trials or pleaded guilty.

Two defendants were in their 20s and the rest were teenagers, all bound by blood and friendship and something more "sinister," McTigue said during his opening statement. All six are alleged members of a violent Central American street gang known as MS-13, and authorities say the attack was gang-motivated. One of them, Shahid Baskerville, will testify against Gomez after striking a deal with prosecutors.

McTigue recounted for jurors the "grim" facts, which he has repeated at three previous trials, all ending in guilty verdicts. The four victims, longtime friends, entered the schoolyard that night hoping to relax and reconnect but were instead "swarmed" in what began as a robbery.

Dashon Harvey and Iofemi Hightower, both 20, and Terrance Aeriel, 18, were then led to a wall and shot in the back of the head. As McTigue spoke, the parents of the victims sat stoic in their customary courtroom seats.

Hightower was also attacked with a machete and Terrance’s sister, Natasha Aeriel, then 19, was sexually assaulted, then shot in the head. Gomez is not alleged to have committed those crimes himself; he is not charged with sexual assault.

Natasha Aeriel survived and has since graduated from college. She will testify next week. At previous trials, she identified two defendants but cannot recall Gomez. Robbins doesn’t dispute his client’s presence at the schoolyard but said the boy didn't play a role in the attack.

Gomez, now 20, sat passively at the defense table, dressed in a blue button-down shirt with black slacks. There was no one from his family in the courtroom.

The prosecutor’s office has acknowledged Gomez’s case will be the most challenging because a statement he gave police will not be allowed at trial, there is no forensic evidence linking him to the crime and the only person who can identify him is Baskerville.

He initially told police Gomez was only "standing around being a bystander," Robbins said, before changing his story last year. Baskerville now alleges Gomez tried to shoot Natasha Aeriel but the gun jammed and never fired. Another defendant admitted he shot all four victims with a different gun.

"Forget what you think you know," Robbins told the jury, then spelled out "Bystander" in marker on a sheet of paper. "The word, ladies and gentleman, accurately, fittingly describes Gerardo."

Later, Troy Bradshaw, who is Terrance and Natasha’s father, just shook his head at that defense. "We know everyone was involved, and we know what happened," he said. "I look at my daughter and I know what happened."